Valve and semiconductor fabricating equipment using the same

ABSTRACT

Disclosed is a gas valve capable of switching gases to be introduced within a vacuum chamber with high speed thereby enhancing the controllability of the composion of a semiconducting thin film growing on a substrate and shortening the time required for growth of the thin film. The gas valve comprises a bendable film between a pair of parallel plate electrodes whereby operating the film by an electrostatic force and opening and closing a port for releasing gas to a substrate mounted on the wall surface of a gas chamber and a port for exhausting an unnecessary gas to an exhaust passage. The gas valve is mounted in the vicinity of the substrate within the vacuum chamber for supplying a working gas in a minimum amount required for the film growth.

This is a division of application Ser. No. 07/890,711, filed May 29,1992, now U.S. Pat. No. 5,284,179.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to a valve and a semiconductor fabricatingequipment using the same, and particularly, to an actuator for openingand closing action in a valve adapted to control a flow rate of fluid,and a semiconductor fabricating equipment for forming a semiconductingfilm on the surface of a substrate by switching different kinds ofsource gases using the above valve.

(2) Description of the Prior Art

There has been disclosed an actuator for a valve or the like used tocontrol a flow rate of a trace of fluid, in Proceedings of the IEEEMicro ElectroMechanical System, pp 95-98, 1990, wherein the actuatorcomprises a sheet having one end being fixed to serve as a valve bodyand an electrode which has a passage port and is disposed on the lowerside of the sheet surface whereby the sheet is displaced by anelectrostatic force for opening and closing the passage port.

Specifically, the above actuator is constituted of a dielectric with apassage port including a plate electrode on a silicon substrate, and avalve body made of a dielectric including a plate electrode for openingand closing the passage port, wherein the sheet is attracted to theelectrode surface by an electrostatic force generated between theelectrodes, to thereby close the passage port provided on a part ofstructure on the electrode side. Meanwhile, the opening of the passageis effected by utilizing a restoring force of the sheet functioning as aspring. In the above actuator, it takes comparatively long time to openand close the passage port. Particularly, the time required for openingthe passage port is restricted by the quickness of the returning of thesheet due to the restoring force thereof and is hence difficult to bemade shortened. Also, the electrostatic force acted in closing thepassage port must be too large to resist the restoring force of thesheet functioning as a spring. The electrostatic force is inverselyproportional to the square of the distance between the electrodes.Accordingly, in order to obtain a sufficient electrostatic force toresist the above restoring force, the above-mentioned conventionalstructure needs to makes smaller the distance between the sheet and theelectrode located under the sheet up to a gap, for example, of severalten μm. Therefore, since a flow rate of fluid is restricted by thedistance between the sheet and the electrode under the sheet, a valveusing the conventional actuator has a difficulty to control a large flowrate of fluid.

The technique of forming a semiconducting film on a semiconductorsubstrate is an important process in the fabrication of semiconductordevices such as IC, and LSI. In general, the epitaxial growth processrequires switching of plural kinds of gases. As shown in FIG. 23, theswitching of gases in a semiconductor fabrication has been carried outwith use of a valve 50 provided in a tube 51 connected with a gas bombdisposed separatedly from a vacuum chamber 49 internally including asubstrate 48 (disclosed, for example, in Japanese Patent Laid-Open No.sho 63-136616).

In the above-mentioned Japanese Patent Laid-Open No. sho 63-136616,there has been proposed a system comprising an opening and closingequipment provided between an epitaxial growth chamber and a gasintroducing vessel whereby gas is exhausted from the gas introducingvessel in closing the opening and closing equipment.

Recently, with micronizing semiconductor devices, the epitaxial growthtechnique is required to form an extremely thinned film, for example, asuperstructure having a layer thickness of at least 1 nm with accuracyof atomic order. As shown in FIG. 23, the prior art includes a long pipefrom a valve 50 to a vacuum chamber 49, which occurs a delay timebetween valve switching and gas-flow switching in the vacuum chamber,and which makes the change in gas pressure slow. Accordingly, for thepurpose of forming a superstructure on a substrate by alternatelyintroducing different kinds of gases within the vacuum chamber, theprior art has disadvantage of not sufficiently controlling the atomicarrangement of the superstructure and of taking a long period of timefor film growth.

Furthermore, the above-mentioned prior art has a large disadvantageaccompanied by supplying gas from the gas introducing vessel. Forexample, it has a difficulty to supply a reaction gas in a minimumamount required for epitaxial growth only in the vicinity of the surfaceof the substrate. This is due to the fact that there has been merelyknown such an opening and closing equipment as being in a grade of ashutter used in a Molecular Beam Epitaxy (MBE). Even in theabove-mentioned Japanese Patent Laid-Open No. sho 63-136616, there hasbeen not disclosed the more concrete form of the opening and closingequipment.

Meanwhile, for making the semiconductor fabrication speedy, there hasbeen proposed a technique of disposing a nozzle in the vicinity of asubstrate to be processed, and of mechanically controlling the port ofthe nozzle for opening and closing action. However, the technique isdisadvantageous in that the mechanical opening and closing action tendsto yield pulsating current of fluid, that is, turbulent flow in a gaspassage, which is unsatisfactory for the fabrication of the abovementioned micro-superstructure or the like.

SUMMARY OF THE INVENTION

It is therefore the primary object of the present invention to realize asemiconductor fabricating equipment capable of accurately formingdifferent kinds of semiconducting layers without requiring a long timefor growth thereof.

It is another object of the present invention to realize a valve capableof switching gases of a large flow rate with high speed and highaccuracy, and hence being adapted for the above-mentioned semiconductorfabricating equipment.

To achieve the above objects, the present invention provides an actuatorrequired for a valve capable of switching fluids with high speed andhigh accuracy and hence being adapted for a semiconductor fabricatingequipment. The actuator comprises: film supporting means for supportingboth ends of a bendable film; a film functioning as a valve body, whichhas the development length longer than a distance between filmsupporting members of the film supporting means and has at least oneinflexion point when being supported by the film supporting means; andoperating means for moving the inflexion point. Namely, the valve isformed by a vessel in which fluid is introduced, ribbon-like film havingat least one inflexion plane movable within said vessel, a plurality ofports provided on the wall of the vessel, and film operating means foropening and closing a plurality of said ports by movement of theinflexion plane of the film.

In a preferred mode, the valve includes a conductive film as the abovefilm and electrodes as the film operating means disposed at bothpositions facing to upper and lower sides of the film surface, wherein avoltage is applied from or to across the conductive film and the upperside electrode and to or from across the conductive film and the lowerside electrode, thus crosswisely moving the inflexion point of the filmwith an electrostatic force. Furthermore, the preferred mode includes atleast one passage port formed on the part of the insulating layer andelectrodes. In this case, by moving the inflexion point of theconductive film, the surface of the conductive film serves as a valvebody for opening and closing the passage port, to thereby form a valvefor controlling a flow rate of fluid.

The above mode may involves such a modification that the film and theoperating means are composed of a magnetic material and anelectromagnet, respectively.

The valve of the present invention functions to move the inflexion pointof the film by the electrostatic force (or electromagnetic force)sequentially from the position where the film and electrode (orelectromagnet) are in close proximity to each other. Consequently, evenwhen the supporting means is long in height, that is, a distance betweenthe upper and lower electrodes (or electromagnets) are enlarged, thefilm can be operated. Therefore, there can be suitably set the distancebetween the electrodes (or electromagnets) disposed on the upper andlower sides of the film to hence enlarge an interval between the passageport and the valve body, thus controlling a large flow rate of fluid.Furthermore, since the opening and closing action in valve isirrespective of the restoring force of the film, it is possible to openand close the passage port of the valve with high speed by theelectrostatic force (or electromagnetic force).

The valve of the present invention comprises electrodes, an insulatinglayer and a metallic film and hence can be fabricated to the size of 10mm or less using semiconductor micro-processing technique. Also, aplurality of valves can be integrated in a unit structure. Furthermore,respective gas outlets of a plurality of the valves are set in amatrix-like arrangement in a unit structure, which makes it possible toindependently operate respective valves with electric signals.

Hereinafter, there will be described a process for fabricating amicro-valve using semiconductor micro-processing technique.

In order to obtain the micro-valve with a size of 10 mm or less, thereis adopted such processes as involving a photolithography technique, apatterning technique for a thin film and a substrate, an etchingtechnique, and a technique using sacrifice layer selectively etched withsolution.

A channel with a depth of several 10 to 100 μm is formed on a siliconsubstrate by anisotropic etching, and an electrode pattern, insulatinglayer and fluid port are formed in the channel. Subsequently, asacrifice layer is also formed in the channel, and a film serving as avalve body is formed on the sacrifice layer in such a manner as to besupported at both the ends by the silicon substrate other than thechannel.

After formation of the film, the sacrifice layer under the film isselectively etched by solution. Consequently, the film is supported bythe silicon substrate at only both the ends thereof, thus forming a filmstructure having an inflexion portion in the channel of the substrate.Subsequently, the thus film structure having the electrode pattern,insulating layer and fluid port is bonded with another substrate havingan electrode pattern, insulating layer and fluid port, to therebyfabricate a micro-valve.

The above-mentioned process is characterized by fabricating themicro-valve with use of two substrates.

Meanwhile, a silicon substrate formed with a hole by anisotropic etchingor electric discharge machinning is assembled to a silicon substrateformed with a first sacrifice layer on the surface, thus obtaining astructure similar to the above-mentioned channel. A second sacrificelayer and a film are formed on the assembled substrates, thereby forminga film structure which is supported by the substrate at both the ends tothus form an inflexion portion, similarly to the above manner.

The film structure thus fabricated may bonded with two substrates eachhaving a fluid port and an insulating layer on an electrode pattern, tothus form a micro-valve.

Furthermore, the present invention provides a semiconductor fabricatingequipment wherein a sample substrate is mounted in a vacuum chamber andgas is supplied within the vacuum chamber by gas supplying means thusforming semiconducting layers on the surface of the substrate. In thiscase, the above gas supplying means includes: a first passage forintroducing gas in the vacuum chamber; a valve of the present inventionprovided on the extreme end of the passage; a second passage forintroducing exhaust gas outside the vacuum chamber. Also, the above gasvalve includes; a port through which necessary gas is supplied to thesubstrate out of the gas supplied through the first passage; a portthrough which exhaust gas is released in the second passage; and gascontrolling means for controlling a ratio of necessary gas to exhaustgas.

In another preferred mode, the above sample substrate and the valve aredisposed within a vacuum chamber with an exhaust port. In this case, thevalve is miniaturized, and the gas port and housing thereof is made of amaterial with a chemical stability to withstand the baking temperaturewithin the vacuum chamber.

In a further preferred mode, there is formed a plurality of ports forsupplying gas to the sample substrate on the valve, thus making the gasdistribution in the vicinity of the surface of the substrate uniform.Also, there may be provided doubled vacuum chambers, wherein a port ofthe valve for supplying gas to the substrate is positioned on the wallof the inner vacuum chamber.

In a still further preferred mode, there is provided a valve mountingchamber for introducing the valve next to a semiconducting layer growthchamber. In the valve mounting chamber, a micro-valve mounted at anextreme end of a pipe is baked under a vacuum similar to that of thegrowth chamber, and is then introduced into the thin film growthchamber. In order to uniformly form the thin film on the substrate,respective positions of the substrate and micro-valve can be suitablyset.

The semiconductor fabricating equipment of the present invention is soconstituted that a valve is disposed in the vicinity of a sample stageto control the gas flow rate in the vicinity of the sample stage withoutany pipe. As a result, epitaxial growth can be effected with such a highspeed as being comparable to that obtained by being injected through anozzle. Furthermore, the valve is operated to distribute the gassupplied at a specified flow rate into a necessary gas for growth ofsemiconducting layers and an exhaust gas. Accordingly, there occurs nopulsating current of gas thereby stabilizing the gas supply, whichenhances the accuracies of thickness of semiconducting layers andmaterial composition. Particularly, in disposing a plurality of ports ofthe gas valve on the same plane facing to the sample stage, gasdistribution in the vicinity of the sample stage is made uniform,resulting in the obtained semiconducting layers with high accuracy.Preferably, the valve has a bendable film which is fixed in a bent formbetween a pair of parallel plate electrodes through an insulating layer.And, by applying a voltage across the film and the electrode, the filmis attracted and moved to the electrode by the electrostatic forcethereby opening and closing the port of a valve having an actuatorformed on a part of the electrode. The thus valve is small in the outershape, has no friction of motion, and can be composed of heat resistingmaterial being less liable to release gas from the surface, differentlyfrom an electromagnetic valve, air valve or the like. Accordingly, thevalve can be directly mounted and operated within the vacuum chamber. Asa result, since the valve can be located closely to the substrate withinthe vacuum chamber, reaction gas can be supplied to the necessaryminimum space. This remarkably improves the controllability of gaspressure in the vicinity of the surface of the sample substrate, whichmakes it possible to accurately control the atomic arrangement of agrowing superstructure, and also to shorten the time required for thefilm growth.

Furthermore, in an integrated micro-valve wherein a plurality ofmicro-valves are set in a matrix-like arrangement on one substrate, eachmicro-valve can be independently opened and closed with electricsignals. This provides such additional functions as selecting a gas tobe introduced within a thin film growth chamber from several kinds ofgases, and as introducing the selected gas to the thin film growthchamber from only a specified one among a plurality of outlets. Thus, aspecified film can be formed on a specified region on the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and advantages and further description will nowbe discussed in connection with the drawings in which:

FIG. 1 is a perspective view including a partial cross section showingan example of an actuator constituting a valve primary part according tothe present invention;

FIG. 2 is a cross sectional view showing an example of an actuatorconstituting a valve primary part according to the present invention;

FIG. 3 is a perspective view including a partial cross section showinganother example of an actuator constituting a valve primary partaccording to the present invention;

FIG. 4 is a cross sectional view showing a further example of anactuator constituting a valve primary part according to the presentinvention;

FIG. 5 is a perspective view including a partial cross section showingan example of a valve according to the present invention;

FIGS. 6A and 6B are schematic cross sectional views of the valve shownin FIG. 5 for explanating the operation thereof;

FIGS. 7A and 7B are a perspective view including a partial cross sectionand a cross sectional view showing an example of an integratedmicro-valve according to the present invention, respectively;

FIG. 8 is a cross sectional view of another example of a laminated typeintegrated micro-valve according to the present invention;

FIGS. 9a to 9k are process diagrams showing an example of a micro-valvefabricating method according to the present invention;

FIGS. 10a to 10k are process diagrams of another example of amicro-valve fabricating method according to the present invention;

FIGS. 11a to 11k are process diagrams of a further example of amicro-valve fabricating method according to the present invention;

FIGS. 12a to 12k are process diagrams of a still further example of amicro-valve fabricating method according to the present invention;

FIGS. 13a to 13m are process diagrams of an additional example of amicro-valve fabricating method according to the present invention;

FIGS. 14a to 14m are process diagrams of an example of combining theexamples as shown in FIGS. 10 to 10k and FIGS. 13a to 13m to each other;

FIG. 15 is a cross sectional view showing an example of an epitaxyequipment according to the present invention;

FIGS. 16A and 16B are graphs showing the relationship between gaspressure and time for explanating the operation of an conventionalepitaxy equipment, respectively;

FIGS. 17A and 17B are graphs showing the relationship between gaspressure and time for explanating the operation of an epitaxy equipmentaccording to the present invention;

FIG. 18 is a cross sectional view showing another example of a valveaccording to the present invention;

FIG. 19 is cross sectional view of another example of an epitaxyequipment according to the present invention;

FIGS. 20A and 20B are cross sectional views showing a further example ofa semiconductor fabricating equipment according to the presentinvention;

FIG. 21 is a perspective view showing an example of a micro-pump usingan actuator according to the present invention;

FIGS. 22a to 22d are schematic cross sectional views for explanating theoperation of the micro-pump as shown in FIG. 21; and

FIG. 23 is a block diagram showing a conventional epitaxy equipment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, the exemplary embodiments of the present invention will bemore detail described with reference to the accompanying drawings.

EXAMPLE 1

FIGS. 1 and 2 is a perspective view including a partial cross sectionand a side cross sectional view showing an example of an actuatorconstituting a primary part of a valve according to the presentinvention, respectively.

In this example, the actuator includes a ribbon-like conductive film 1,two film supporting structures 2-1 and 2-2 for supporting both the endsof the film, and upper and lower operating units 3-1 and 3-2respectively supported by the supporting structures 2-1 and 2-2 foroperating the film 1. The film 1 is supported in such a manner as toform a S-shaped inflexion portion within tile film 1, and accordingly,the length of the film 1 is set to be longer than an interval betweenthe film supporting structures 2-1 and 2-2 with a height of, forexample, 3 mm.

The film 1 is operated by the operating units 3-1 and 3-2 in such amanner that the curved plane (inflexion portion) 1-S is moved. Theoperating units 3-1 and 3-2 are constituted such that the portionsfacing to the upper and lower surfaces of the film 1 are made to beflat, respectively. As a voltage is applied across the operating unit3-1 and the film 1, the upper surface of the film 1 is brought inclose-contact with the lower surface of the operating unit 3-1sequentially from the supporting structure 2-1 to 2-2 side. At the sametime, the lower surface of the film 1 being in contact with the uppersurface of the lower operating unit 3-2 is separated from the operatingunit 3-2 sequentially in the direction from the supporting structure 2-1to 2-2 side, thus moving the curved plane 1-S to the supportingstructure 2-2 side.

Specifically, the actuator includes the operating unit 3-1 having anelectrode disposed on the upper side of the conductive film 1 through aninsulating layer 4 of a thickness of 2 μm or less, and the operatingunit 3-2 having an electrode disposed on the lower side of theconductive film through an insulating layer 5 of a thickness of 2 μm orless. By switching a voltage applied by a switching circuit 6 from or toacross the electrode of the operating unit 3-1 and the conductive film 1to or from across the electrode of the operating unit 3-2 and theconductive film 1, the S-shaped inflexion portion 1-S of the film 1supported by the film supporting structures 2-1 and 2-2 is crosswiselymoved by the electrostatic force. A translucent electrode made of ITO(Indium Tin Oxide) may be used as the electrode of the electrostaticactuator, which makes easy the observation of movement of the S-shapedplane caused by the applied voltage to thereby support the maintenance.

The height of the supporting structures 2-1 and 2-2 is determined basedon the thickness of the film 1, curvature radius of the curved plane,loss resistance caused by fluid flow and the like. In general, with thethinned thickness of the film 1, the reduced elastic coefficient, andthe increased curvature radius of the curved plane, the height of thefilm 1 can be reduced.

Furthermore, each of the insulating films 4 and 5 needs a thicknessenough to resist against dielectric breakdown in applying a voltageacross the conductive film 1 and the electrode for operating the film 1.The insulating layer 4 and 5 can be formed by using the conventionaltechnique of evaporation or chemical reaction growth of an insulatingmaterial, holding of an insulating sheet, coating of insulating agent orthe like. The insulating material may be coated not only on theelectrodes of the operating units 3-1 and 3-2 but also on the surface ofthe film 1. Also, in order to effectively obtain the operating force dueto the electrostatic force, there may be used an insulating materialhaving a high dielectric constant so as to thin the thickness of theinsulating layer without occurring dielectric breakdown.

As the material of the conductive film, there is used a film made of acomposite material sticked with the above conductive material. In thiscase, the film comprises; a metallic film of aluminum, gold, platinum,chrome, iron, nickel, permalloy, or molybdenum; an alloy film made of astainless steel or the like; and a film of polyimide resin, polyester,silicon, silicon nitride, silicon oxide, PBN (Pyrolytic Boron Nitride)or the like, on which surface the metallic or alloy film is formed.

EXAMPLE 2

FIG. 3 is a perspective view including a partial cross section showinganother example of an actuator constituting a primary part of a valveaccording to the present invention. In this example, the film 1 includestwo inflexion planes 1-1i and 1-2i each having an integral-sign-shape ofa smooth slope, and the other structure is the same as in FIG. 1. Eachof the two inflexion planes 1-1i and 1-2i has a smooth and simplecurvature radius compared with the S-shaped plane, and is easilyfabricated. Also, the curvature radius is made larger, and the gap oftwo operating units in which the fill acts can be reduced. Therefore,the actuator of this example is adapted for miniaturization of thevalve.

Meanwhile, the film 1 having the curved plane formed in a S-shape has aneffect that, because the bend thereof is pushed between the surfaces ofthe operating units located on the upper and lower sides of the film,the film 1 is prevented from being deflected with its dead weight whennot being attracted by the operating units. Accordingly, it has anadvantage of enlarging the interval between two supporting structurestwice in the case of the integral-sign-shape. For the applications, theshape of the curved plane of the film 1 is selected to be the integral-sign-shape or the S-shape.

EXAMPLE 3

FIG. 4 is a cross section showing a further example of an actuatorconstituting a primary port of a valve according to the presentinvention. This example is characterized by operating the inflexionplane of the film by utilizing electromagnetic force as the filmoperating means.

The principle of the operation is the same as shown in FIG. 1. A film 7is composed of a magnetic metallic film made of permalloy having athickness of 5 μm. An operating unit includes electromagnets 8-1 and 8-2respectively disposed on the upper and lower sides of the magnetic film7. By switching the current flow from or to the electromagnet 8-1 to orfrom the electromagnet 8-2 with a switching circuit 9, a S-shape plane7-1 of the magnetic film 7 is crosswisely moved by the electromagneticforce.

The magnetic film 7 is made of a magnetic film of iron, nickel, or analloy thereof such as permalloy, or a composite material obtained bycoating or evaporating the powder of the above metal or alloy or mixturethereof on the film of polyimide, polyester, silicon, silicon nitride,or silicon oxide. A superconductive material may be used as the magneticmaterial. Furthermore, an electromagnet or superconductive magnet may beused as the film operating unit to operate the film by applying currentto a coil pattern formed on the upper and lower surfaces of the film.

The film 7 may be made of a shape memory alloy. The film made of theshape memory alloy previously storing the flat shape is plasticallydeformed into a S-shape in low temperatures, and both the ends thereofare rigidly supported to thus assemble an actuator, and thereafter, thefilm is heated at a martensite transformation temperature or more. Withthis method, the actuator can be assembled while deforming the film intoa S-shape, to thereby make easy the fabrication process.

EXAMPLE 4

FIG. 5 is a perspective view including a partial cross section showingan example of a valve according to the present invention.

In FIG. 5, a valve includes a bendable metallic film 1 serving as avalve body, supporting structures 2 for supporting both the ends of thefilm 1, side walls 11 of the valve (the broken-out section shows thestate of removing the side wall), and a pair of upper and lower plateelectrodes 12 and 12' respectively each having an insulating film onthe-surface facing to the film 1. The flat electrodes 12 and 12' areprovided with outlets 13 and an exhaust port 14, respectively. By movingan integral-shape planes of the film 1 crosswisely using the plateelectrodes 12 and 12', the outlets 13 and the exhaust port 14 can beopened and closed. Namely, a part of the film 1 serves as a valve bodyfor opening and closing the passage ports 13 and 14. Accordingly, gas issupplied from a gas supply tube 10 and a supply port 15 provided on thesupporting structures 2 to a gas flow-in chamber sealing the plateelectrodes. The outlets 13 and exhaust port 14 are fluidly connectedwith a gas chamber and exhaust port, respectively, so that the gas canbe supplied through the outlets 13 or exhausted through exhaust port 14,respectively. In this example, the metallic film 1 is made of stainlesssteel having a thickness of 5 μm. The flat electrodes 12 and 12' aremade of a single crystalline silicon wafer doped with impurities, andtheir surfaces to be brought in contact with the film 1 are insulatedwith thermal oxidized films having a thickness of approximately 1.5 μm,respectively.

The valve is opened and closed by applying a direct voltage of severalvolts across the film 1 and upper or lower electrode, and consequentlythe flow-out of gas is switched to the outlets 13 or the exhaust port14.

The valve, used for flow control, naturally needs to determine itsmaterial and dimensions based on the necessary flow rate, used pressure,kinds of gases and the like. The pressure drop and conductance in thepassage is due to the cross section of the ports and the amount of thegap between two operating units for operating the film. The valve ofthis example has a feature of suitably determining these parameters.Also, the time required for opening and closing the valve is to bewithin several tens milli-seconds. The material of the film 1 ispreferably selected according to the kinds of the used gases. Thethickness of the film 1 is preferably determined based on the magnitudeof the load exerted on the film surface due to the pressure difference,and allowable deformed amount of the film surface. Also, this exampleinvolves the structural modifications such as change in number of portsand in combination thereof, and functional alternation.

FIGS. 6A and 6B are schematic cross sectional views of the valve asshown in FIG. 5 for explanating the operation thereof. FIG. 6A shows thestate where gas is made to flow-out from outlets 13 when a voltage isapplied from a power supply 16 to a lower electrode 12' side. FIG. 6Bshows the state where gas is made to flow-out from an exhaust port 14when a voltage is applied from a power supply 17 to an upper electrode12 side.

Incidentally, the evacuation of the passage on the exhaust side can beeffected, as required.

The material used in the above-mentioned gas valve has the chemicallystabilized surface enough to withstand the temperature of approximately300° C. of the baking carried out for increasing the degree of vacuum ina vacuum chamber.

EXAMPLE 5

FIGS. 7A and 7B are a perspective view including a partial crosssectionand a cross sectional view of an example of an integrated gas valveaccording to the present invention.

This embodiment is commonly provided with a plurality of valves in amatrix-like arrangement according to plural kinds of gases therebyalternately introducing gases into a semiconducting layer growthchamber. For avoiding the complexity, these figures show only the casein which three valves are integrated into a unit structure.

In the above figures, three valves 301, 302 and 303 operated accordingto the same principle are integrated, and are provided with gas supplypipings 311, 312 and 313, and exhaust pipings 321, 322 and 323,respectively.

The valve 301 includes a bendable metallic film 331 serving as a valvebody, and a pair of plate electrodes 341 and 344 each having aninsulating layer 340 on the surface. A gas outlet 351 and exhaust port356 are provided on the parts of a pair of the electrodes 341 and 344,respectively. Gas is supplied from a gas supply port 361. In thisexample, the metallic film 331 is made of stainless steel having athickness of 5 μm. The plate electrode 341 is made of a singlecrystalline silicon wafer doped with impurities for reducing resistivityor a metallic thin film formed on a single crystalline silicon wafer. Inorder to insulate the metallic film 331 from the flat electrode 341 or344, there are formed SiO₂ films each having a thickness of 0.5 to 2.5μm on the surfaces of the plate electrodes 341 and 344 being contactwith the metallic film 331. In addition, a SiC plate may be used inplace of the above insulating layer.

In the valve 301, by switching the voltage of 50 to 300 V applied acrossthe film and the upper or lower electrode, the gas flow can be switchedfrom or to the outlet 351 and to or from the exhaust port 356.

The valves 302 and 303 are made of the same material as that of thevalve 301, and are provided with metallic films 331 and 333, outlets 352and 353, and exhaust ports 357 and 358, respectively. The exhaust ports356, 357, 358 are connected with exhaust tubes 321, 322 and 323,respectively. The supply ports 361, 362 and 363 are connected with thegas supply tubes 311, 312 and 313, respectively.

In FIG. 7B, only the gas 372 is introduced in a thin film growthchamber, and the other gases 371 and 372 are exhausted.

The valve 302 shows the case where a voltage is applied across the lowerelectrode 344 and the film 332 which allows gas to flow-out from theoutlet 352. Meanwhile, the valve 303 shows the case where a voltage isapplied across the upper electrode 343 and the film 333, which allowsgas to flow-out from the exhaust port 358.

In the integrated valve, the upper electrode, lower electrode and filmof each valve are insulated from each other. Also, by controlling thevoltage applied to respective valves 301, 302 and 303, the gas to beintroduced into the thin film growth chamber can be selected.

The integral valve of this example makes it possible to switch pluralkinds of gases by the valve with a small capacity. As a result, aplurality of valves can be provided on the wall surface of the growthchamber or within the growth chamber.

In this example, different kinds of gases are introduced to the supplyports of respective valves, thus selecting the kind of gas to besupplied into the growth chamber. However, in the case of supplying thesame gas to each valve, gas can be supplied from different ports.

EXAMPLE 6

FIG. 8 is a cross sectional view of another example of a laminate typeintegrated gas valve according to the present invention.

This is a laminated type integrated gas valve obtained by laminating theintegrated valves as shown in FIGS. 7A and 7B in a mutistage, and hassuch functions as of selecting the gas to be introduced into asemiconducting layer growth chamber from several kinds of gases 371, 372and 373, and of introducing the selected gas from only the specifiedoutlet among plural number of outlets 411, 412 and 413 to the thin filmgrowth chamber.

The laminated integrated valve includes two integrated valves 431 and433, and a gas channel structure 432 for connecting the integratedvalves 431 and 433 to each other.

The integrated valve 433 includes three valves 441, 442 and 443. Bycontrolling voltages applied to respective valves 441, 442 and 443, thegas to be introduced into a semiconducting layer growth chamber isselected from three kinds of gases 371, 372 and 373. In this figure,there is shown the case where only the gas 371 supplied to the valve 441is introduced to the gas channel structure 432 and the other gases 372and 373 are exhausted. The construction thereof is substantially similarto that of the integrated valves as shown in FIGS. 7A and 7B.Accordingly, the same parts are indicated at the same numerals and theexplanation thereof is omitted.

The gas channel structure 432 includes a first gas channel fordistributing the gas from a plurality of outlets of the integrated valve433 into a plurality of supply ports 451, 452 and 453, and a second gaschannel 470 for collectively exhausting (471) the gas from a pluralityof exhaust ports of the integrated valve 431.

The first gas channel and the second gas channel 470 are independentlyformed in the gas channel structure 432.

The gas 371 selected by the integrated valve 433 is introduced torespective valves 446, 447 and 448 of the integrated valve 431 throughthe first channel of the gas channel structure 432 and a plurality ofsupply ports 451, 452 and 453 of the integrated valve 431. The gas 371is then introduced from only the specified outlet among plural outlets411, 412 and 413 to a semiconducting layer growth chamber. Similarly tothe lower integrated valve, the upper integrated valve is constitutedsuch that voltages applied on respective valves 446, 447 and 448 arecontrolled to switch the valves 446, 447 and 448. As a result, theoutlets through which gas is introduced into the growth chamber can beselected. FIG. 8 shows the case where valves 446 and 448 are opened andthe valve 447 is closed, which causes the selected gas 371 to beintroduced into the growth chamber from the outlets 411 and 413. In thevalve 447, the gas not to be introduced into the thin film growthchamber is exhausted through an exhaust channel 470 formed in the gaschannel structure 432.

The laminated type integrated valve makes it possible to select the gasto be introduced into the thin film growth chamber among various kindsof gases, and to introduce the selected gas into the growth chamber fromthe specified outlet among a plurality of outlets, thus enabling theformation of the thin film at the specified region on the substrate.

In this example, the diameter and pitch of the outlet is specified to be10 μm and 1 mm, respectively. In this case, by switching the gas to beintroduced into the thin film growth chamber using the laminatedintegrated valve, approximately 10×10 μm² of the thin film isselectively formed on the substrate at a pitch of 1 mm. Incidentally,the average free path of the gas introduced from the outlet issufficiently long compared with the distance between the outlet and thesubstrate.

In FIGS. 7A and 7B, and FIG. 8, respective valves are arranged in asingle line to simplify the drawings; however, in actual, the outlets ofa plurality of valves are set in a matrix-like attangement toward aplume.

EXAMPLE 7

FIGS. 9a to 9k show fabricating processes of an example of a valvefabricating method according to the present invention. Hereinafter, thefabricating processes will be described in detail.

(1) Formation of Channel on Silicon Substrate (FIGS. 9a and 9b)

A channel 120-1 having a cross width of 5 mm, length of 10 mm and depthof approximately 50 to 100 μm is formed on a silicon wafer 110-1 havinga thickness of 39 μm by anisotropic etching.

The etchant used in the anisotropic etching is a 40% potassiumhydroxide, and the temperature of the solution is kept at 70° C. Inusing a silicon wafer having a crystal face orientation of (100) on thesubstrate surface, the crystal face orientation of the side wall of thechannel is to be (111).

(2) Formation of Electrode Pattern and Fluid Port (FIG. 9b)

A fluid port 125 and an aluminum electrode pattern 121 are formed in thechannel 120-1 formed in (1) by photolithography, CVD, or sputtering. Aninsulating layer 122 made of a silicon oxide film or silicon nitridefilm is formed on the electrode pattern 121 to a thickness of several μmby sputtering or CVD.

The fluid port 125 may be formed by techniques other than etching, suchas, electric discharge machinning.

(3) Formation of Sacrifice Layer (FIG. 9c)

A photoresist 130-1 is spin coated on the silicon wafer 110-1 having thechannel of a depth of approximately 50 to 100 μm formed with theelectrode pattern and insulating layer, which are fabricated in (2). Theviscosity of the photoresist and the rotational number of a spinner aredetermined in such a manner that the slope of the wall of the channel120-1 is smoothly coated with the resist.

After coating on the silicon wafer, the photoresist is subjected topatterning by exposure and developing. Consequently, the photoresist130-1 remains only on the channel 120-1 of the silicon wafer, whichserves as a sacrifice layer.

(4) Formation of Film With Bend Plane (FIGS. 9d to 9e)

On the silicon wafer 110-1 subjected to photoresist pattering in (3),there is formed a metallic film 140 made of aluminum, nickel or the liketo a thickness of several μm by evaporation, sputtering, CVD, or thelike. The metallic thin film thus formed is subjected to pattering.

The silicon wafer 110-1 is then dipped in an etching solution toselectively etch only the photoresist 130-1 under the metallic thinfilm, so that the metallic film is formed into such a bridge structureas to be supported at its both ends by the silicon wafer.

(5) Assembly of Valve (FIGS. 9e to 9k)

Another silicon wafer 110-2 having a fluid port 125 and an insulatinglayer 122 on an electrode pattern 121 is bonded to the silicon wafer110-1 having the metallic film in a matrix-like arrangement in thechannel fabricated in (4), to thus fabricate a film electrostatic valvehaving a bend plane, as shown in FIGS. 9i to 9k.

The silicon wafer 110-2 is formed with a projection having a heightequal to a depth of the channel 120 of the silicon wafer fabricated in(4). As an adhesive agent, there is used a polyimide resin capable ofkeeping its adhesiveness under high temperatures of 100° to 300° C. orlead glass capable of acting as an adhesive under comparatively lowtemperatures of 300° to 400° C.

FIG. 9k shows a three-way valve mechanism wherein fluid ports areprovided on the upper and lower electrode plates, and gas inlets areprovided on the upper and lower electrode plates or side walls of thevalve, respectively.

Meanwhile, by providing two or more of fluid ports on the upper andlower electrode plates, there is obtained such a valve as being capableof discretely changing the gas flow accompanied by movement of the film.Also, by setting a plurality of the above-mentioned valves on thesilicon wafer in a matrix-like arrangement, it is possible to fabricatethe integrated flow control element.

EXAMPLE 8

FIGS. 10a to 10k show fabrication processes of another example of avalve fabricating method according to the present invention. The exampleas shown by FIGS. 9a to 9k is characterized by fabricating the filmhaving a S-shape plane in the channel 120-1 formed on the silicon wafer10-1 by etching, and consequently has the following disadvantages:

1 The depth of the channel, which defines the stroke of the valvefabricated by bonding the silicon wafers, is limited by the thickness ofthe silicon wafer. As a result, it is difficult to obtain the stroke of100 μm or more.

2 In drying the substrate having the film after etching the sacrificelayer under the film, it is difficult to prevent the film from beingbrought in close-contact with the silicon wafer by the surface tensionof the solution.

In order to solve the above disadvantages, this example as shown inFIGS. 10a to 10k uses two silicon wafers and two sacrifice layers andforms a micro-valve having the channel structure similar to theabove-mentioned example as shown in FIGS. 9a to 9k.

(1) Formation of Channel on Silicon Substrate

A first thin silicon wafer 110-3 having a face orientation of (100) anda thickness of 220 μm is formed with a hole 150-1 using anisotropicetching or electric discharge machinning, as shown in FIGS. 10a and 10b.

The etchant used in the anisotropic etching is 40% potassium hydroxide,and the temperature of the solution is kept at 70° C.

A photoresist 131-1 being a first sacrifice layer is spin coated on thesurface of a second silicon wafer 110-4, as shown in FIG. 10i. Thesilicon wafer 110-3 having the hole 150-1 is then located on thephotoresist 131-1 of the second wafer 110-4. Subsequently, the twosilicon wafers are aligned to be then temporarily bonded, as shown inFIG. 10c. By using the thus two silicon wafers 110-3 and 110-4, therecan be obtained the structure similar to the channel of the example asshown in FIGS. 9a to 9b.

In the above structure, the thickness 220 μm of the silicon wafer 110-3is equivalent to the stroke of the valve, to thus obtain the valve witha large stroke.

(2) Formation of Sacrifice Layer

A photoresist (second sacrifice layer) is spin coated on the two siliconwafers 110-3 and 110-4 having the channel with a depth of 220 μmfabricated in (1), as shown in FIG. 10d.

The viscosity of the photoresist and rotational number of the spinner isdetermined so as to smoothly coat the wall slope of the channel with theresist. Subsequently, the photoresist is subjected to pattering byexposure and developing. Thus, the photoresist 130-2 (second sacrificelayer) remains only in the channel of the silicon wafer, which serves asthe sacrifice layer, as shown in FIG. 10d.

(3) Formation of Film Having Bend Plane

A metallic film 140 made of aluminum, nickel or the like is formed onthe two silicon wafers after photoresist patterning fabricated in (2) toa thickness of several μm by evaporation, sputtering, CVD or the like.After that, the metallic film 140 is subjected to patterning byphotolithography, as shown in FIG. 10e.

The two silicon wafers 110-3 and 110-4 are dipped in an etchingsolution, so that only the photoresist 130-2 under the metallic film andthe photoresist 131-1 between the silicon wafers 110-3 and 110-4 areselectively etched. Accordingly, the two silicon wafers are separatedfrom each other, thus forming the metallic film having a bridgestructure of being supported at only both the ends by the silicon wafer110-3, as shown in FIG. 10f.

There may be formed such a channel (not shown) for allowing the etchingsolution to easily enter the silicon wafer 110-4 for uniformly andeasily etching the sacrifice layer.

(4) Assembly of Valve

Two silicon wafers 110-5 and 110-6 each having a port 125 and aninsulating layer 122 on an electrode pattern 121 are aligned and bondedon both sides of the silicon wafer 110-3 (having the metallic thin filmformed into a bridge shape at the hole portion) fabricated in (3), tothus fabricate the valve having the film with a bend portion, as shownin FIGS. 10g, 10j, 10k and 10h. The silicon wafer 110-6 has a projection180-2 with a height of 220 μm equal to the depth of the hole (thicknessof the silicon wafer 110-3).

EXAMPLE 9

FIGS. 11a to 11k show fabrication processes of a further example of avalve fabricating method according to the present invention. A filmelectrostatic micro-valve of this example is obtained by fabricating aS-shaped film using two silicon wafers in the same manner as shown inExample 8 expect the following point. Namely, as shown in FIG. 11b, whena silicon wafer 110-3 having a hole 150-1 is temporarily bonded on asilicon wafer 110-4 having a photoresist being a sacrifice layer, thebonded surface of the silicon wafer 110-3 is reversed to that shown inFIG. 10b. Compared with the example as shown 10a to 10k, this exampleinvolves a difficulty in forming the photoresist 130-3 in a channelafter bonding the two silicon wafers, as shown in FIG. 11d. However,when the photoresist under the film formed in the channel is etched andthereafter such a silicon wafer as supporting only both the ends of thefilm is taken out of solution, this example has an effect that the filmis less liable to be brought in close-contact with the slope of thehole. Thus, it is possible to easily fabricate a structure of supportingboth the ends of the film by the silicon wafer, as shown in FIG. 11f.

EXAMPLE 10

FIGS. 12a to 12k show fabricating processes of a still further exampleof a valve fabrication method capable of suitably setting the valvestroke described in the Examples 8 and 9. The fabrication methodsaccording to Examples 8 and 9 are disadvantageous in that since thevalve stroke is equivalent to the thickness of the silicon wafer 110-3having a hole 150-1, it is one-sidely determined depending on thethickness of the used silicon wafer. In the fabrication method of thisexample, several times of processes of patterning, etching and the likeare added to the processes shown in the Examples 8 and 9, to suitablydetermine the stroke of the micro-valve. Hereinafter, this fabricationmethod will be described.

(1) Formation of Channel of Silicon Substrate

Several ten μm of a step 120-2 is formed on the rear surface of asilicon wafer 110-7 having a thickness of 390 μm by anisotropic etching,as shown in FIG. 12b. Subsequently, a hole 150-2 is formed on a part ofthe step 120-2 using anisotropic etching or electric dischargemachinning again, as shown in FIG. 12b.

The etchant used in the anisotropic etching is 40% potassium hydroxide,and the temperature of the solution is kept at 70° C. The faceorientation of the silicon wafer surface is (100), and the faceorientation of the slope of the hole is (111).

A photoresist 131-2 serving as a first sacrifice layer is spin coated onthe surface of a silicon wafer 110-8 having a projection with a heightequal to that of the step 120-2 formed on the rear surface of thesilicon wafer 110-7, as shown in FIG. 12i. The silicon wafer 110-7having the hole is located on the photoresist 131-2 of the silicon wafer110-8, and the two wafers 110-7 and 110-8 are aligned and temporarilybonded, as shown in FIG. 12c. Thus, by using the two silicon wafers110-7 and 110-8, there can be formed the same channel as that of Example7 as shown in FIGS. 9a to 9b.

In this case, the valve stroke is obtained by subtracting the height ofthe step 120-2 formed on the rear surface from the thickness of thesilicon wafer 110-7. Accordingly, by suitably controlling the etchingamount for the rear surface, the valve stroke can be suitablydetermined.

For example, letting the height of the step be 90 μm or 140 μm, thestroke is 300 μm or 250 μm.

(2) Formation of Sacrifice Layer

A photoresist layer 130-3 (second sacrifice layer) is spin coated on thetemporarily bonded two silicon wafers 110-7 and 110-8 having the channel150-2 with, for example, a depth of 30 μm fabricated in (1), as shown inFIG. 12d. The viscosity of the photoresist and the rotational member ofa spinner is determined so as to smoothly coat the slope surface of thechannel with the photoresist.

Subsequently, the photoresist is subjected to patterning by exposure anddeveloping. Thus, the photoresist 130-3 (second sacrifice layer) remainsonly in the channel of the silicon wafer, which serves as a sacrificelayer.

(3) Formation of Film With Bend Plane

A metallic thin film 140 made of aluminum, nickel or the like having athickness of several ten μm is formed on the two silicon wafers 110-7and 110-8 after photoresist patterning fabricated in (2) by evaporation,sputtering, CVD or the like. The metallic thin film is then subjected topatterning by photolithography, as shown in FIG. 12e.

The two silicon wafers 110-7 and 110-8 are dipped into etching solutionso as to selectively etch only the photoresist 130-3 under the metallicthin film and the photoresist 131-2 between the silicon wafers 110-7 and110-8. Consequently, the two silicon wafers are separated from eachother, and the metallic thin film is formed into a bridge structure ofbeing supported at both the ends by the silicon wafer 110-7, as shown inFIG. 12f.

Incidentally, there may be formed a channel (not shown) through whichthe etching solution for the sacrifice layer easily enters in thesilicon wafer 110-8, so that the sacrifice layer can be uniformly etchedfor a shortened time.

(4) Assembly of Valve

The silicon wafer 110-7 (having the metallic thin film formed into abridge shape at a hole portion) fabricated in (3) is bonded on both thesides with a silicon wafer 110-9 having a fluid port and an electrodepattern covered with an insulating layer on the surface of a projection190, and a silicon wafer 110-10 having a fluid port, an electrodecovered with an insulating layer, and a projection 180-4, to thusfabricate a valve having the film with a bend plane, shown in FIGS. 12f,12g, 12h, 12j and 12k. In addition, the height of the projection 180-4of the silicon wafer 110-10 is equivalent to the stroke of the valve.

EXAMPLE 11

FIGS. 13a to 13m show fabricating processes of an additional example ofa valve fabricating method according to the present invention.

(1) Formation of Channel of Silicon Substrate

A channel 120-3 having a depth of a several ten μm is formed on asilicon wafer 110-11 having a thickness of 390 μm by anisotropicetching.

The etchant used in the anisotropic etching is 40% potassium hydroxide,and the temperature of the solution is kept at 70° C.

(2) Formation of Electrode Pattern and Fluid Port

A fluid port 125 and an aluminum electrode pattern 121 are formed in thechannel 120-3 formed in (1) by photolithography, etching or the like.Subsequently, an insulating layer 122 made of silicon oxide film orsilicon nitride film having a thickness of several μm or less bysputtering, CVD or the like, as shown in FIG. 13b.

(3) Formation of Sacrifice Layer

1 An aluminum serving as a first sacrifice layer 160-1 is formed on thesilicon wafer 110-11 having the electrode pattern 121 and the insulatinglayer 122 in the channel with the depth of several μm fabricated in (2).

2 A polysilicon serving as a second sacrifice layer 161-1 is formed onthe aluminum serving as the first sacrifice layer, to flatten thesubstrate, as shown in FIG. 13c.

3 A resist 162 is coated on the substrate, and is subjected topatterning by photolithography, as shown in FIG. 13d.

4 The second sacrifice layer 161-2 is processed by dry etching or ionmilling (ion beam machinning), as shown in FIG. 13e. In this, case, theprocessing direction can be suitably selected by changing the ion beamat an angle to the substrate. The selection ratio of the processingspeed between the second sacrifice layer 161-1 and the first sacrificerlayer 160-1 is larger, and consequently the processing is stopped whenthe second sacrifice layer 161-1 is processed, as shown in FIG. 13e.

Subsequently, the resist on the surface of the substrate is removed.Incidentally, in the case where the resist exerts no effect on themechanical and electrical properties of the metallic film fabricated inthe later process, the resist does not needs to be removed.

(4) Formation of Film With Bend Plane

A metallic film 140 made of nickel or the like having a thickness ofseveral μm is formed on the silicon wafer 110-11 with the sacrificelayer fabricated in (3) by evaporation, sputtering, CVD or the like.

In forming the thin film by CVD, the step of the sacrifice layer can beuniformly formed with the metallic film.

After that, the metallic film is subjected to patterning byphotolithography, as shown in FIG. 13f.

(5) Assembly of Valve

The silicon wafer 110-11 (having the metallic film formed into a bridgeshape in the channel) fabricated in (4) is aligned with another siliconwafer 110-12 having a fluid port and an insulating layer 122 on theelectrode pattern 121, to thereby fabricate a S-shaped filmelectrostatic valve, as shown in FIGS. 13h to 13j.

In the above valve, upon bonding, by pushing the step of the metallicfilm by the projection 180-5 of the silicon wafer 110-12, hence from abend on the metallic film using only the flat portion thereof.Accordingly, the film which is movable part of the valve fabricated inthis method has a uniform internal stress, thereby causing the film tosmoothly move compared with Examples 7, 8, 9 and 10.

The silicon wafer 110-12 has a projection 180-5 with a height equal tothe depth of the channel 120-3 of the silicon wafer fabricated in (4).

As an adhesive agent, there is used a polyimide resin havingadhesiveness to withstand high temperatures of 100° to 300° C. or a leadglass capable of showing adhesiveness under relatively low temperaturesof 300° to 400° C.

In this example as shown in FIGS. 13a to 13m, the channel is formedwithin one silicon wafer, and a film structure serving as a valve bodyis formed using the channel. However, when the valve stroke is intendedto be changed or the problem of the film sticking to the substrateshould be solved, the fabricating methods of Example 8 to 10 areapplicable.

EXAMPLE 12

FIGS. 14a to 14m show an example of combining Example 8 with Example 11of a valve fabricating method according to the present invention. Asshown in FIGS. 14a to 14m, there is provided a channel 100 for easilyetching the sacrifice layer. In this figure, the same parts areindicated at the same numerals and the explanation thereof is omitted.

In the above-mentioned examples of a valve fabricating method, thephotoresist is used as the sacrifice layer, and the sacrifice layer iscoated in the channel of the silicon wafer, to thus obtain a filmstructure. As the sacrifice layer, there may be used such a material asto be selectively etched against the valve structure, other than theabove mentioned photoresist, aluminum and polysilicon. The filmstructure can be formed by combining the channel of the silicon waferwith dry etching and ion milling (ion beam machinning).

With use of the above mentioned processes, it is possible to fabricate afluid integrated circuit obtained by integrating valves, pumps andintegrated circuits for controlling these elements within the siliconwafer.

EXAMPLE 13

FIG. 15 is a cross sectional view showing an example of a semiconductorfabricating equipment using the above valve according to the presentinvention.

In order to grow a superstructure (crystal material having a structureof being artificially controlled to laminate films each having athickness in atomic order) on a substrate 20, there are disposed two gasvalves 21-1 and 21-2 within a vacuum chamber (semiconducting thin filmgrowth chamber). Also, the substrate 20 is mounted on a sample stage 19within the vacuum chamber 18. In this example, a plurality of kinds ofgases are alternately introduced within the vacuum chamber 18 to growthe superstructure on the substrate 20, and consequently a plurality ofgas valves are disposed according to the kinds of gases. However, toavoid the complexity, this figure shows only two gas valves 21-1 and21-2.

The gas valves 21-1 and 21-2 are externally connected with gas supplytubes 22-1 and 22-2, gas exhaust tubes 23-1 and 23-2, three lead wires(not shown) adapted to apply a voltage for opening and closing thevalves, lead wires (not shown) connected with heaters 24-1 and 24-2 forheating the whole valves to prevent deposition of reaction gas, and thelike, respectively. These tubes and lead wires are introduced within thevacuum chamber 18 through flanges 27-1 and 27-2 removably attached tothe wall surface of the vacuum chamber 18.

The semiconductor fabricating equipment of this example is characterizedby introducing a plurality of valves within the vacuum chamber. Comparedwith the conventional equipment where the gas valves are connected withthe vacuum chamber through long pipes, this equipment is advantageous inthat the release of excess gas not to contribute to epitaxial growth onthe substrate 20 is reduced and the rapid switching of the gases isrealized. Particularly, on supplying gas, the gas flow in the passage iskept constant, and the rapid gas switching can be achieved withoutyielding the turbulent flow because the outlet 13 and exhaust port 14are controlled to be switched by the metallic film 1 within the gasvalves 21-1 and 21-2. As a result, it is possible to accurately controlthe atomic arrangement of extremely thin layers such as asuperstructure, and also to shorten the time required for growth of thefilm.

FIGS. 16A and 16B show the relationship between gas pressure and timewith respect to gases A and B which is alternately supplied in thevicinity of a sample substrate controlled for epitaxial growth by theconventional equipment as shown in FIG. 23.

FIGS. 17A and 17B show the relationship between gas pressure and timewith respect to the gases A and B in the vicinity of the substrate 20controlled by the epitaxy equipment of this example. As will be apparentfrom the comparison between FIGS. 16A and 16B, and FIGS. 17A and 17B,according to this example, it is possible to shorten the time requiredfor transient pressure change accompanied by switching the gases A and Band hence to extremely improve the controllability of gas pressure onthe surface of the substrate.

In the gas valves 21-1 and 21-2 used in this example, under theprinciple thereof, a plurality of outlets can be arranged in one gasvalve. This leads to the following two effects. An effect lies in thatgas molecules can be uniformly supplied from the gas valve 21 disposedin the vicinity of the substrate 20 for epitaxial growth to the surfaceof the substrate. In uniformly supplying gas on the surface of thesubstrate by injecting gas from a single port, there is required thesufficient distance between the port and the substrate. In this case,excess gas not to contribute the growth is released within the vacuumchamber, thus lowering the controllability. In this example, the releaseof the excess gas not to contribute is reduced thereby realizing therapid gas switching performance. Another effect lies in that the gasflow is changeable by one gas valve 21.

EXAMPLE 14

FIG. 18 is a cross sectional view showing another example of a valve ofthe present invention. An upper plate electrode 37-1 and lower plateelectrode 37-2 are divided into a plurality of electrodes, respectively,and a voltage is selectively applied from a power supply 38 to a partof, or all of the above divided electrodes, thus limiting the valve topartially or wholly opened and closed. FIG. 18 shows only the wiringform of the lower electrode 37-2 to avoid the complexity. A voltage fromthe power supply 38 is applied to respective divided electrodes of thelower plate electrode 37-2 through switches S1, S2, S3 . . . S7 providedaccording to the divided electrodes. The same wiring is effected on theupper electrode 37-1. Therefore, the electrostatic force can be exertedin the defined regions of the upper and lower electrodes, so that gasflow is changeable by selecting a port of a plurality of the outlets 33.

In this example, by sequentially opening and closing a plurality ofports, gas flow is discretely controlled. Furthermore, by setting theoutlets in a matrix-like arrangement, the range of controlling the flowof the used gas can be enlarged. Incidentally, with the servicecondition, the shape of the curved plane in the film 1 is determined. Inthis case, the film 1 can be commonly applicable with respect to themechanism, material operation, control and the like except for thedifference in the shape of the curved plane.

EXAMPLE 15

FIG. 19 is a cross sectional view showing another example of asemiconductor fabricating equipment according to the present invention.In this example, for further rapidly switching different gases, a secondvacuum chamber 42 is formed in a first vacuum chamber 41, and a samplesubstrate 48 for epitaxial growth is disposed in the vacuum chamber 42.

Valves 43 and 44 are disposed on the wall surface of the second vacuumchamber 42. Gases alternately introduced through outlets of valves 43and 44 into chamber 42 are then directly exhausted outside the equipmentfrom an exhaust pipe 45. Gases not introduced through outlets of valves43 and 44 into chamber 42 are exhausted outside the equipment fromexhaust pipes of valves 43 and 44 During gas is released from the valve43, the gas pressure within the second chamber 42 is kept to be 10⁻³Torr. Meanwhile, the interior of the first chamber is kept to be in anultra-high vacuum of 10⁻⁹ Torr by a main exhauster 46. In switching thekinds of gases, a film valve 43 is closed and also a film valve 47connecting the first and second chambers 41 and 42 with each other isfully opened, to thereby rapidly exhaust the gas within the secondchamber 42. After that, by immediately closing the valve 47 and openingthe valve 44, a new gas is supplied into the second chamber 42 to growthe next epitaxial layer on the substrate 48. The operation is repeated,and therefore, it is possible to rapidly supply and exhaust gas in thevicinity of the substrate.

EXAMPLE 16

FIGS. 20A and 20B show a primary part of a further example of asemiconducting thin film fabricating equipment. The primary part of thethin film fabricating equipment includes a semiconducting layer growthchamber 201, valve mounting chamber 204, sample substrate 240 and amicro-valve 203. The thin film growth chamber 201 and the valve mountingchamber 204 are partitioned from each other by a gate valve 210.

The micro-valve 203 for switching gases to be introduced in the thinfilm growth chamber 201 is attached at the extreme end of a pipe withinthe valve mounting chamber 204, and is baked in the same degree ofvacuum as in the growth chamber, as shown in FIG. 20A. Then, the gatevalve 210 partitioning the growth chamber from the valve mountingchamber is opened, and the micro-valve 203 is conveyed within the thinfilm growth chamber 201, as shown in FIG. 20B. The thin film fabricatingequipment of this example, the valve 203 is mounted or dismounted withinthe valve mounting chamber disposed independently from the growthchamber, so that the valve 203 can be mounted or dismounted under thecondition of keeping the growth chamber at an ultra-high vacuum. In thethin film fabricating equipment of this example, the switching of gasesis effected in the vicinity of the substrate 240, similarly to theabove-mentioned examples. Accordingly, it is possible to extremelyreduce a dead space in the piping which has been troublesome and henceto rapidly supply and exhaust the gas to be introduced in the growthchamber. This enables the accurate control of crystallinity of asemiconducting thin film. Furthermore, after exhausting the gas, thepressure in the thin film growth chamber can be returned to anultra-high vacuum within a period of at least one second.

In the examples as shown in FIGS. 15 and 19, the valve is mounted on thewall of the growth chamber so that the mounting or dismounting needs torelease the vacuum of the growth chamber once and evacuate it to anultra-high vacuum again, and consequently the maintenance and exchangeof the valve takes a period of several days. Meanwhile, this example asshown in FIGS. 20A and 20B includes the valve mounting chamber, whichmakes easy the mounting of the valve thereby reducing the periodrequired for the mounting to be half a day.

In the thin film fabricating equipment of this example, the distancebetween the micro-valve and the substrate can be suitably determinedwith use of a conveyance rod for the micro-valve. This makes it possibleto control the distance between the micro-valve and the substrate basedon the change in kinds of gases and pressure in the growth chamber, andhence to usually form an uniform thin film on the substrate.

In any one of the epitaxy equipments of Examples 13, 15 and 16, for thespecified kind of gas to be introduced in the vacuum chamber, the gas isheated from room temperature to enhance the partial pressure: thereof,and is then introduced the vacuum chamber. In this case, when the partof the pipe is in low temperatures, gas is solidified to be deposited onthe part, which often causes the trouble on operation of the equipment.To avoid the trouble, a heater is disposed on the part of the valves forheating the whole mechanism thereof. The heater is energized from theexternal power supply to be heated. This mechanism eliminates blockingof the fine hole of the nozzle and generation of deposits on the surfaceof the film.

In the above-mentioned example, a single crystalline silicon is used asthe plate electrode; however, other material such as dielectricsubstance having a high dielectric constant may be used. Such materialincludes ceramic, such as SiC. The plate electrode made of such materialneeds no insulating treatment for its surface being in contact with thefilm. Meanwhile, current is allowed to flow between the film and theelectrode thereby generating Joule's heat. With use of the Joule's heat,the whole valve structure can be heated, to thus prevent the depositionof reaction gas on the passage.

The valve urging an electrostatic or electromagnetic force is adapted tocontrol the flow rate of fluid, particularly, a rarefied gas used undera low pressure. The reason for this is that, by only changing the heightof the film supporting structures, there can be suitably set an intervalof a passage put between operating units formed on upper and lower sidesof the film serving as a valve body. Also, since the opening and closingof the valve is irrespective of the restoring force of the film itself,it is possible to perform high speed opening and closing action in valvedue to an electrostatic force or electromagnetic force. The film-likevalve body has a function of covering particles or the like in a micronorder, and hence promotes the effect of sealing passage ports when dustor the like exists between the valve body and the valve seat, whichmakes the leakage of gas extremely small. The valve is alsominiaturized, and hence includes passage ports in a matrix-likearrangement in the small area, thus being adapted to control a rarefiedgas in uniform diffusion and to discretely control a flow rate thereof.

In the epitaxy equipment of the present invention wherein the abovevalve is provided within the vacuum chamber, there is realized the rapidswitching of different gases without turbulent flow within the vacuumchamber, which makes it possible to accurately control atomicarrangement of the growing superstructure.

Furthermore, the above-mentioned equipment shortens the transientswitching time in alternately introducing different gases within thevacuum chamber, to thereby shorten the time required for growth of thefilm.

EXAMPLE 17

FIGS. 21, and FIGS. 22a to 22d show an example of a micro-pump using anelectrostatic actuator of the present invention. FIG. 21 is a view of aprimary part of the micro-pump, and FIG. 22a to 22d are views showingthe operating principle thereof.

The pump as shown in FIG. 21 has a structure obtained by laminating anelectrostatic valve 501 and an electrostatic pump operating unit 502,which are operated under the same operating principle. The valve 501 andpump operating unit 502 are independently operated by electric signals.

The valve 501 is composed of a three-way valve having a piping forsupporting fluid and a piping for exhausting fluid. In order to avoidthe complexity, the pipings are not shown.

The valve 501 includes a bendable metallic film 503-1 serving as a valvebody, a pair of plate electrodes 505-1 and 505-2 each having aninsulating film 504 formed on the surface. An outlet 506-2 and exhaustport 506-1 are provided on parts of a pair of plate electrode,respectively. Fluid is supplied from a supply port (not shown) formed onthe part of the plate electrode having the exhaust port 506-1. In thisexample, a metallic film 503-1 is composed of stainless steel having athickness of 5 μm. The material of the plate electrode 505 is composedof a single crystalline silicon wafer having the reduced resistivityupon doting with impurities, or a metallic film formed on the singlecrystalline silicon wafer. A thermal oxidized film having a thickness of0.5 to 2.5 μm is formed on the surface of the plate electrode being incontact with the metallic film 503 to insulate the metallic film fromthe plate electrode. Incidentally, a SiC plate may be used in place ofthe above electrode and the insulating film.

The valve 501 can switches the flow of fluid between the outlet side andthe exhaust port side by switching the voltage of 50 to 300 V appliedacross the film 501 and the upper or lower electrode 505.

When the valve 501 is operated with a.c. voltage, the film 503-1 servingas a valve bodys is vertically oscillated. Accordingly, by changing thefrequency of the applied voltage, the flow of fluid passing through thevalve 501 is made to be continuously changed.

With use of the above valve 501, fluid is introduced within the pumpoperating unit 502 laminated on the valve 501. When fluid is unnecessaryto be introduced within the pump operating unit 502, the fluid isexhausted by switching the valve 501.

The pump operating unit 502 laminated on the above valve 501 is operatedby an electrostatic force similarly to the valve 501. The structure ofthe pump operating unit 502 is different from the above valve in thefollowing points.

1 Width of film 503-2

The pump operating unit is operated to exhaust fluid by moving the film503-2. Accordingly, the film 503-2 has a width enough to be inclose-contact with the side wall of the operating unit structure at theside surface thereof. In addition, the gap of 100 μm between the filmand pump operating unit is remarkably smaller than the film width of 10mm, so that the amount of fluid passing through the gap in movement ofthe film is substantially negligible.

2 Shape of film 503-2

The pump operating unit 502 as shown in FIG. 21 is operated to introducegas from a hole 507 formed on the portion of the film 503-2. The holeportion 507-1 of the film is fixed on the insulating layer 504 under thefilm, and consequently the movement of the film by the electrostaticforce is effected on the left side of the hole.

The operation of the pump will be described below with reference toFIGS. 22a to 22d. These figures show a structure obtained by laminatinga one-way valve 508 for preventing the counterflow of fluid and aswitching valve 501 for introducing fluid to the pump operating unit onthe upper and lower sides of the pump operating unit, respectively. Theelectrostatic valve 501 operated in the same principle as in the pumpoperating unit is provided on the lower side (fluid supply side to thepump) of the pump operating unit 502. Meanwhile, a one-way valve 508 isprovided on the upper side (fluid exhaust side from the pump) of thepump operating unit 502. The operating procedure of the pump will bedescribed below.

(1) Introduction of Fluid to Pump Operating Unit

By applying a voltage across the lower electrode 505-2 of the valve 501and tile film 503-1, the S-shaped plane of the film 503-1 is moved inthe left direction. Thus, the outlet 506-2 of the valve 501 is openedand the exhaust port 506-1 is closed. Accordingly, the fluid supplied tothe valve 501 is introduced to a chamber 509-1 within the pump operatingunit 502 through the outlet 506-2. In addition, for avoiding thecomplexity, the port through which fluid is supplied to the valve 501 isomitted.

The fluid is introduced through a supply port 506-4 and a hole 507formed on the part of the film 503-2. In this case, the film 503-2 ofthe pump operating unit closes the outlet 506-3, as shown in FIG. 23a.

Subsequently, by applying a voltage across the lower electrode 505-4 ofthe pump operating unit 502 and the film 503-2, the film 503-2 is movedin the left direction, as shown in FIG. 23b.

(2) Exhaust of Fluid From Pump Operating Unit

By applying a voltage across the upper electrode 505-1 of the valve 501and the film 503-1, the film 503-1 is moved in the right direction.Thus, the outlet 506-2 of the valve 501 is closed and the exhaust port506-1 is opened. Accordingly, fluid supplied to the valve 501 is made toflow to the exhaust port 506-2, as shown in FIG. 23c.

Subsequently, by applying a voltage across the upper electrode 505-3 ofthe pump operating unit 502 and the film 503-2, the film 503-2 is movedin the left direction. Consequently, fluid filling the chamber 509-1within the pump operating unit is exhausted through the upper one-wayvalve 508, as shown in FIG. 23d.

In closing the chamber 509-2 of the pump operating unit 502, thepressure of the chamber 509-2 within the pump operating unit is changedaccompanied by movement of the film of the pump operating unit, so thatthe film is exerted with a load due to the pressure difference betweenthe chambers 509-1 and 509-2 in addition to the electrostatic force.Accordingly, in order to move the film from end to end, theelectrostatic force is required to be larger than the load due to thepressure difference.

When the pump deals with a fluid in a large amount, the change inpressure of the chamber 509-2 within the pump operating unit is madelarger thus making larger the pressure difference between in thechambers 509-1 and 509-2. As a result, it is difficult to operate thevalve with the electrostatic force.

In order to solve the above problem, there is provided a channel whichconnects the chamber 509-2 to the gas source (not shown) connected withthe valve supply port 506-1, within the pump thereby preventingoccurrence of the pressure difference between in the chambers 509-1 and509-2. By providing such a channel, even in movement of the film 503-2of the pump operating unit 502, the pressure in the chamber 509-2 withinthe pump is made equal to the gas pressure of the gas source (pressureof the chamber 509-1 within the pump), thus easily moving the film 503-2by the electrostatic force.

In the structure as shown in FIG. 21, the fluid exhausted from the pumpoperating unit is, as required, introduced within the pump operatingunit 502 by switching the valve 501 located under the pump operatingunit, and is exhausted from the pump operating unit 502. Since theswitching of the fluid exhausted from the pump operating unit iseffected by the valve 501 laminated under the pump operating unit, thedead space is made smaller and the gas can be rapidly exhausted from thepump.

Furthermore, in integrating such structures (laminated structure ofintegrated pumps and integrated valves), the integrated valve areconnected with the pipes for supplying various kinds of gases thereto,and are electrically operated independently from each other, thusselecting the gas to be introduced within the pump operating units.Meanwhile, the pump operating units are electrically operatedindependently from each other, thus exhausting the gas from the suitableposition of the outlet of the pump operating units.

FIGS. 22a to 22d show the structure of laminating the electrostaticoperated valve for preventing counterflow of the fluid and a one-wayvalve on the upper and lower sides of the pump operating unit,respectively. In this case, there can be disposed electrostatic valvesoperated with the same operating principle as the pump operating unit onthe upper and lower sides of the pump operating unit, respectively. Byfurther laminating the above valves and the pump operating units, fluidis sequentially supplied. By forming the above valve and pump to beseveral mm cube or less in size, and laminating them in multi-stages,there can be obtained a structure of supplying a small amount of fluidwith electric signals.

The above valve and pump are substantially the same structure, and canbe integrated on the same substrate. In this case, there can be obtainedan integrated flow control system integrated with flow elements such asthe valve and pump operating unit on one substrate.

I claim:
 1. A semiconductor fabricating equipment wherein a wafer togrow a semiconductor thin film layer is mounted on a sample stage withina chamber and at least one kind of reaction gas is supplied in saidchamber by at least one gas supplying means thereby forming asemiconducting thin film on a surface of said wafer,said gas supplyingmeans comprising:a first passage for introducing gas within saidchamber; a gas valve provided on the extreme end of said passage; and asecond passage for introducing an unnecessary gas which does notcontribute to forming the semiconducting film and which is within saidgas valve to outside of said chamber, and said gas valve comprising:aport for releasing a necessary gas contributing to forming thesemiconducting film among the gases supplied through said first passageto said wafer; a port for releasing the unnecessary gas to said secondpassage; and gas amount controlling means for controlling a ratio ofsaid necessary gas to said unnecessary gas.
 2. A semiconductorfabricating equipment according to claim 1, wherein said gas valvecomprises:a vessel filled with gas; a film having at-least one inflexionplane movable within said vessel; a plurality of ports provided on awall of said vessel; and film operating means for opening and closingthe plurality of ports by movement of said inflexion plane of said film.3. A semiconductor fabricating equipment according to claim 2, whereinsaid gas valve further includes means for controlling the temperature ofsaid gas valve.
 4. A semiconductor fabricating equipment according toclaim 2, wherein at least a part of said film is conductive, and saidfilm operating means includes at least one electrode provided on thewall of the vessel facing upper and lower sides of said film, means forapplying a voltage across said electrode and said film, and a controlcircuit for controlling said voltage.
 5. A semiconductor fabricatingequipment according to claim 2, said film is made of a magneticmaterial, and said film operating means comprises magnetic forcegenerating means provided on the wall of the vessel facing the upper andlower sides of said magnetic film.
 6. A semiconductor fabricatingequipment according to claim 2, wherein said gas valve is disposed insuch a manner that the plurality of ports thereof face to said wafer. 7.A semiconductor fabricating equipment according to claim 2, wherein saidgas valve is mounted on a wall surface of a semiconducting thin filmgrowth chamber within said chamber.
 8. A semiconductor fabricatingequipment wherein a second chamber is disposed in a first chamber, awafer to grow a semiconductor thin film layer is mounted on a samplestage within said second chamber, and reaction gas is supplied withinsaid second chamber by at least one gas supplying means, to thereby forma semiconducting thin film on the surface of said wafer,said gassupplying means comprising:a first passage for introducing gas withinsaid chamber; a gas valve provided on the extreme end of said passage;and a second passage for introducing an unnecessary gas which does notcontribute to forming the semiconducting film and which is within saidgas valve to outside of said chamber, and said gas valve comprising:aport for releasing a necessary gas which contributes to forming thesemiconducting film among the gases supplied through said first passageto said wafer; a port for releasing the unnecessary gas to said secondpassage; and gas amount controlling means for controlling a ratio ofsaid necessary gas to said unnecessary gas, and said second chamberfurther comprising:a valve for controlling the communication of gasbetween said first chamber and second chamber; and a pipe forintroducing gas within said second chamber to outside of said firstchamber.
 9. A semiconductor fabricating equipment according to claim 8,wherein said valve comprises:a vessel filled with gas; a film having atleast one inflexion plane movable within said vessel; a plurality ofports provided on a wall of said vessel; and film operating means foropening and closing the plurality of ports by movement of said inflexionplane of said film.
 10. A semiconductor fabricating equipmentcomprising:a semiconducting thin film growth chamber; and an integratedvalve having a plurality of valves integrated on a unit structure,wherein each of said valves comprises:gas supply; gas exhaust ports; gasoutlet ports; a bendable film; electrodes covered with insulating layerfor operating said film by an electrostatic force; a piping forsupplying gas to said gas supply ports; a piping for exhausting gas fromsaid gas exhaust ports; and operating means for applying a voltage tosaid electrodes of each of said valves thereby operating said film. 11.A semiconductor fabricating equipment according to claim 10, whereinrespective gas outlets of said plurality of valves are arrangedtwo-dimensionally.
 12. A semiconductor fabricating equipment accordingto claim 10, wherein said semiconducting thin film growth chamber iscapable of being independently vacuum-evacuated and comprises:a firstchamber for mounting said valve; a second chamber which is a samplechamber for internally mounting a sample substrate to grow asemiconducting thin film; and a means for moving a plurality of outletsof said integrated valve to said second chamber in carrying out thesemiconducting thin film growth, which is provided between said firstand second chambers.
 13. A process for fabricating a micro-valveincluding a plurality of ports on a wall of a vessel, and a film havingan inflexion plane movable within said vessel, electrodes covered withinsulating layer in the wall of said vessel for opening and closing theplurality of ports by movement of said inflexion plane of said film,comprising:a. a first step of preparing a first substrate including achannel having at least one port and an electrode on the bottom thereof;b. a second step of forming a soluble sacrifice layer on the bottomportion of said channel; c. a third step of laminating a conductivematerial on said sacrifice layer, and then removing said sacrificelayer, thereby forming such a conductive film member that both endsthereof is supported by the first substrate near said channel and asupporting portion thereof is separated from the bottom portion of saidchannel; and d. a fourth step of aligning and bonding a second substratehaving an insulating layer, an electrode and port to said firstsubstrate on a side thereof opposed to the bottom portion of saidchannel with respect to said film member, to thereby form a vessel. 14.A process for fabricating a micro-valve according to claim 13, whereinsaid second step including the steps of:forming a first solublesacrifice layer in the bottom of said channel and a second sacrificelayer on said first sacrifice layer; coating a resist on said secondsacrifice layer and carrying out patterning of said resist; andprocessing the shape of said second sacrifice layer using the patternedresist and removing the resist.
 15. A process for fabricating amicro-valve according to claim 13, wherein said first and secondsubstrates are made of silicon.
 16. A process for fabricating amicro-valve including a plurality of ports on a wall surface of avessel, and a film having at least one inflexion plane within saidvessel, and electrodes covered with an insulating layer for opening andclosing a plurality of ports by movement of said inflexion plane of saidfilm, comprising:a. a first step of forming a hole serving as theinterior of said vessel on a first substrate; b. a second step offorming a first sacrifice layer on a second substrate, and aligning saidfirst substrate on said first sacrifice layer; c. a third step offorming a second sacrifice layer on the bottom of a hole portion wheresaid first sacrifice layer obtained in said second step is bottomed; d.a fourth step of laminating a conductive material on said secondsacrifice layer, then removing said first and second sacrifice layersand also said second substrate, thereby forming such a conductive filmthat both ends of said conductive material is supported by the substratenear the side walls of said hole; e. a fifth step of preparing saidthird and fourth substrates each having an electrode and at least oneport; and f. a sixth step of rigidly fixing said third and fourthsubstrates on both sides of said conductive film, respectively.
 17. Aprocess for fabricating a micro-valve according to claim 16, whereinsaid first step includes the step of sleppedly forming said hole of saidfirst substrate such that lower portion of said hole is larger than anupper portion of said hole; and said second step including the step offorming a projection on a surface of said second substrate, saidprojection being wider than the upper portion of said hole and narrowerthan the lower portion of said hole.
 18. A process for fabricating amicro-valve according to claim 16, wherein said second step includes thestep of forming a plurality of channels for passing etching solution forthe sacrifice layer therethrough on said second substrate in thethickness direction.
 19. A process for fabricating a micro-valveaccording to claim 16, wherein said first, third and fourth substratesare made of silicon.